Guard units for the cutter wheels of stump cutting machines generally consist of a metal hood that is welded or otherwise fixed to the machine frame in a covering relation with a forward portion of the cutter wheel. Additionally, these guard units are of a small size relative to the cutter wheel so as not to engage a stump during a cutting operation. This relation between the cutter wheel and the guard unit permits a working clearance of the guard unit with a stump during the manipulation of the cutter wheel in a stump removing operation. Although some of these guard units are pivotally supported or hinged, rather than fixed, on the machine frame, this pivotal action is for the convenience of moving the guard unit into a position for exposing the cutting teeth for maintenance or replacement purposes.